1. Field of the Invention
The present invention relates generally to methods and apparatuses for monitoring and/or controlling pests, as might be particularly useful for monitoring and/or controlling a population of termites.
2. Description of the Prior Art
Many types of termites are soil dwellers (i.e., subterranean termites) and exist in large colonies that can contain several million termites. Members of the colony forage for food and burrow galleries or passageways in the soil outwardly from the colony or nest, and portions of food located by foraging termites are returned to the nest. Termites can be very destructive because of their voracious appetite, especially for wood or other cellulosic materials. The ability of termites to cause considerable damage is in part due to the fact that the termites and external signs of damage caused by the termites are typically not seen until termite infestation is at a relatively advanced stage. Termites are difficult to detect and control because they are cryptic creatures that usually cause damage to the interiors of wooden structures, or otherwise in places that are not readily observable. Accordingly, the control of termites requires enormous expenditures.
Traditional methods for controlling pests such as termites include preventive measures such as pre-treatment of new construction sites with pesticidal agents to prevent subsequent infestation by pests. Under this pre-treatment approach, pesticides are typically sprayed over and into the soil prior to construction of a structure in an attempt to establish a termite barrier around the perimeter of the new structure. For example, the soil present at a new construction site can be pre-treated by trenching, that is, digging a trench in the soil so that the trench surrounds the area to be occupied by the structure and depositing a relatively large amount of pesticide in the trench. Unfortunately, such barriers are often broken or otherwise disturbed during the construction process. This approach also requires that the soil be periodically re-treated in order to maintain the effectiveness of the barrier in precluding termite invasion. After a termite colony discovers one or more discontinuities in a termite barrier, the pretreated building is susceptible to termite attack.
Other traditional methods for controlling termites involve post-infestation efforts. For example, one method utilizes pressure injection of pesticides to directly treat termite galleries. Another approach involves fumigation of a structure infested by termites by tightly tenting (i.e., closing or sealing) the structure and filling the tent with gaseous pesticide. These traditional methods fail, however, to provide any means for satisfactorily detecting termite infestation. These traditional treatments are also inadequate because they only affect those termites which come into direct contact with the pesticides, which is often only a small portion of the subterranean termite population. In addition, precautions must be taken to avoid exposing non-target species and the environment to the pesticides.
A more recent development in termite control technology pertains to the use of a termite bait matrix containing a relatively small amount of a pesticide, such as a termiticide. In general, such methods and apparatuses are directed to controlling pests once they have been detected as a result of a monitoring procedure. After detection, the pests are controlled by inducing the pests to ingest or otherwise come into contact with a toxicant in a bait matrix which is attractive to pests, particularly pests from a specific nest or colony.
More specifically, termites communicate the location of a food source to other termites within their colony by chemical signals such as pheromones. These characteristics may be exploited to effectively control pest infestations. In the course of traveling to the nest, an insect may leave highly specific trail pheromones which direct or recruit other insects to a food source. Subsequently, other insects, usually from the same colony, detect the chemical signal and are thus directed to that food source. The concentration and composition of these pheromones can be species and colony specific, and trail pheromones may be very different from feeding-initiating pheromones. Deposit of specific pheromones in a toxicant-containing matrix food source, i.e., a bait matrix, by foraging insects aids in recruiting other nestmates to the toxicant-containing matrix, whereupon they forage, are exposed to toxicant, and deposit more pheromone, thus creating a cyclical control method. Toxicants to be delivered to insect populations are preferably slow-acting, lethal at concentrations which do not repel target insects, and capable of being combined with an insect food. Insects directly contacting or ingesting the toxicant will not be killed immediately, but will travel to their colony to recruit other nestmates to the toxicant, thereby resulting in the control of large numbers of colony members due to interactions with the colony before death occurs.
In providing methods and apparatuses for monitoring and/or controlling pests (i.e., delivery of toxicant to pests), it is advantageous to minimize disruption to a site where pests have begun feeding. Where such a site is located in the soil, site disruption is minimized, for instance, as described in PCT international publication 93/05004 and U. S. Pat. No. 5,329,726, by using a station housing which is permanently fixed into the soil and capable of being periodically refilled with replacement monitoring and/or toxicant-containing bait matrices.
Termite baiting systems provide significant advantages over the traditional methods of controlling termites. Significantly, efficacious termite baiting systems typically require dramatically lower amounts of pesticide to control or eliminate termite infestations and may reduce the risk of pesticide exposure to non-target species and the environment. Typically, termite baiting systems or stations that have heretofore been disclosed require removal of the contents of the delivery station housing (i.e., the pest food source used for pest monitoring or the pest baiting matrix containing pesticide) to determine whether termites are present or not. The disruption caused by removal of the inner contents is believed to lead in some cases to the pests' premature abandonment of termite bait stations. In this regard, the efficacy of termite bait systems that have heretofore been provided is severely hampered because the termites that feed on the inner contents are sufficiently disturbed by the removal of the inner contents that the termites abandon the bait station before they have ingested sufficient pesticide to control the target termite colony.
Despite the availability of such termite baiting systems, it will be appreciated from the foregoing that there exists a need in the art for termite baiting stations in which station abandonment by termites is reduced. There also exists a need for improved devices and methods for delivering termiticides that can be used for controlling or eliminating termites above, on or below ground.